Valency (chemistry)
From Biocrawler, the free encyclopedia.
In chemistry, valency is the power of an atom of an element to combine with other atoms measured by the number of electrons which an atom will give, take, or share to form a chemical bond. This is related to the number of spaces left in an atom's electron shells. The adjective describing an atom's valency uses a Greek prefix (sometimes such as mono, b\di, tri, tetra etc. for valencies of 1, 2, 3, 4. Main group elements that are metals generally have only one valency, equal to the number of electrons in the valence shell. Transition metals frequently have several valencies (see list below).
The term valency isn't used much today (many textbooks do not even mention it), as the more precise term oxidation state is generally preferred. For a simple ionic compound the oxidation state of a metal will usually be equal to the valency. However for covalent compounds involving nonmetals there is often a difference.
List
List of common valencies for the first 103 elements in order of atomic number:
| Atomic number | Name of element | Valency | ||
|---|---|---|---|---|
| 1 | Hydrogen | 1 | ||
| 2 | Helium | 0 | ||
| 3 | Lithium | 1 | ||
| 4 | Beryllium | 2 | ||
| 5 | Boron | 3 | ||
| 6 | Carbon | 2, 4 | ||
| 7 | Nitrogen | 3, 5 | ||
| 8 | Oxygen | 2 | ||
| 9 | Fluorine | 1 | ||
| 10 | Neon | 0 | ||
| 11 | Sodium | 1 | ||
| 12 | Magnesium | 2 | ||
| 13 | Aluminium | 3 | ||
| 14 | Silicon | 4 | ||
| 15 | Phosphorus | 3, 5 | ||
| 16 | Sulfur | 2, 4, 6 | ||
| 17 | Chlorine | 1, 3, 5, 7 | ||
| 18 | Argon | 0 | ||
| 19 | Potassium | 1 | ||
| 20 | Calcium | 3, 5 | ||
| 21 | Scandium | 3 | ||
| 22 | Titanium | 3, 4 | ||
| 23 | Vanadium | 2, 3, 4, 5 | ||
| 24 | Chromium | 0, 2, 3, 6 | ||
| 25 | Manganese | 2, 3, 4, 6, 7 | ||
| 26 | Iron | 0, 2, 3 | ||
| 27 | Cobalt | 2, 3 | ||
| 28 | Nickel | 0, 2, 3 | ||
| 29 | Copper | 1, 2 | ||
| 30 | Zinc | 2 | ||
| 31 | Gallium | 2, 3 | ||
| 32 | Germanium | 4 | ||
| 33 | Arsenic | 3, 5 | ||
| 34 | Selenium | 2, 4, 6 | ||
| 35 | Bromine | 1, 3, 5, 7 | ||
| 36 | Krypton | 0 | ||
| 37 | Rubidium | 1 | ||
| 38 | Strontium | 2 | ||
| 39 | Yttrium | 3 | ||
| 40 | Zirconium | 4 | ||
| 41 | Niobium | 3, 5 | ||
| 42 | Molybdenum | 0, 2, 3, 4, 5, 6 | ||
| 43 | Technetium | 2, 3, 4, 6, 7 | ||
| 44 | Ruthenium | 0, 3, 4, 6, 8 | ||
| 45 | Rhodium | 3, 4 | ||
| 46 | Palladium | 0, 2, 4 | ||
| 47 | Silver | 1 | ||
| 48 | Cadmium | 2 | ||
| 49 | Indium | 1, 3 | ||
| 50 | Tin | 2, 4 | ||
| 51 | Antimony | 3, 5 | ||
| 52 | Tellurium | 2, 4, 6 | ||
| 53 | Iodine | 1, 3, 5, 7 | ||
| 54 | Xenon | 0 | ||
| 55 | Caesium | 1 | ||
| 56 | Barium | 2 | ||
| 57 | Lanthanum | 3 | ||
| 58 | Cerium | 3, 4 | ||
| 59 | Praseodymium | 3 | ||
| 60 | Neodymium | 3 | ||
| 61 | Promethium | 3 | ||
| 62 | Samarium | 2, 3 | ||
| 63 | Europium | 2, 3 | ||
| 64 | Gadolinium | 3 | ||
| 65 | Terbium | 3 | ||
| 66 | Dysprosium | 3 | ||
| 67 | Holmium | 3 | ||
| 68 | Erbium | 3 | ||
| 69 | Thulium | 2, 3 | ||
| 70 | Ytterbium | 2, 3 | ||
| 71 | Lutetium | 3 | ||
| 72 | Hafnium | 4 | ||
| 73 | Tantalum | 3, 5 | ||
| 74 | Tungsten | 0, 2, 4, 5, 6 | ||
| 75 | Rhenium | 1, 4, 7 | ||
| 76 | Osmium | 0, 2, 3, 4, 6, 8 | ||
| 77 | Iridium | 3, 4 | ||
| 78 | Platinum | 0, 2, 4 | ||
| 79 | Gold | 1, 3 | ||
| 80 | Mercury | 1, 2 | ||
| 81 | Thallium | 1, 3 | ||
| 82 | Lead | 2, 4 | ||
| 83 | Bismuth | 3, 5 | ||
| 84 | Polonium | 2, 3, 4 | ||
| 85 | Astatine | 1, 3, 5, 7 | ||
| 86 | Radon | 0 | ||
| 87 | Francium | 1 | ||
| 88 | Radium | 2 | ||
| 89 | Actinium | 3 | ||
| 90 | Thorium | 4 | ||
| 91 | Protactinium | 4, 5 | ||
| 92 | Uranium | 3, 4, 5, 6 | ||
| 93 | Neptunium | 2, 3, 4, 5, 6 | ||
| 94 | Plutonium | 2, 3, 4, 5, 6 | ||
| 95 | Americium | 2, 3, 4, 5, 6 | ||
| 96 | Curium | 2, 3, 4 | ||
| 97 | Berkelium | 2, 3, 4 | ||
| 98 | Californium | 2, 3, 4 | ||
| 99 | Einsteinium | 2, 3 | ||
| 100 | Fermium | 2, 3 | ||
| 101 | Mendelevium | 2, 3 | ||
| 102 | Nobelium | 2, 3 | ||
| 103 | Lawrencium | 3 |
